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Biomedical subjects

A N Williams

Publications and source records attributed to A N Williams.

11 recordsLinked to original sources
PubMed1992

A standard person-years approach to estimating lifetime cancer risk. The Section of Chronic Disease and Environmental Epidemiology Minnesota Department of Health.

Several methods have been used to estimate the lifetime probability of cancer, such as simple cumulative incidence or competing risk models. These methods are characterized by either simplistic assumptions or detailed computations. The standard person-years method, that parallels cohort analyses, offers a simpler and more accurate method of approximating the lifetime risks of cancer. Since lifetime cancer risk refers to the aggregate risk to a cohort rather than the risk to an individual, it is suggested that a new term, population cancer risk, be used in describing these risks. A reasonable definition for the population cancer risk is the expected number of cancers in the lifetimes of 1,000 people. Estimates of lifetime risks of cancer are interpreted best as a composite measure of the joint forces of cancer morbidity and all-cause mortality at a point in time. The overall population cancer risk (lifetime risk) for residents of Minnesota (United States) is calculated to be 465 cancers/1,000 people; national data provide similar results.

Adolescent↗
PubMed1992

Effects of prior exposure to cocaine: interaction of reinforcing and suppressant effects.

Squirrel monkeys were trained to respond under second-order schedules of food presentation and then sequentially exposed to either a self-administration (SA) and then a conditioned taste aversion (CTA) procedure, or a CTA procedure and then a SA procedure. Initial exposure to stimuli associated with post-session delivery of cocaine (0.3 mg/kg) either maintained (SA) or suppressed (CTA) responding, respectively. In contrast, following exposure to CTA, SA procedures failed to maintain levels of responding comparable to those seen with initial exposure to SA. Following exposure to SA, the CTA procedure failed to suppress responding. Thus, prior exposure to either the reinforcing or suppressant effects of cocaine modified its subsequent behavioral effects, suggesting a unique role for behavioral history in the abuse potential of cocaine.

Animals↗
PubMed1991

Effects of asbestos-related pleural disease on pulmonary function.

The relationship between loss of pulmonary function and the presence of asbestos-related pleural disease was evaluated for 913 Minnesota asbestos workers. Asbestos-related pleural disease was categorized as circumscribed plaques or diffuse thickening. Compared with workers with normal pleura, workers with plaques had a decreased mean percentage for predicted forced vital capacity (FVC) and predicted forced expiratory volume in 1 s (FEV1.0). Diffuse thickening was associated with more profound decreases in FVC and FEV1.0. No relationship was seen between FEV % [(100 x FEV1.0)/FVC)] and either type of pleural disease. Dyspnea was associated with diffuse thickening more so than plaques. These results remained after control for pack-years of smoking, extent of parenchymal disease, and the presence of pulmonary disease history. Pleural plaques and diffuse pleural thickening were considered independent risk factors for the loss of lung function.

Asbestosis↗
PubMed1990

Use of coded mortality data to assess area cancer rates: impact of residence reporting and coding errors.

In spite of their limitations, mortality data are used in many epidemiologic and public health settings. In this investigation, the authors examined the extent to which community cancer mortality rates were affected by incorrect reporting or coding of residence on death certificates. Observed and expected cancer mortality for two adjacent communities in northern rural Minnesota for the periods 1970-1974 and 1980-1984 were obtained from computerized state mortality data. Using statewide rates to obtain expected values, standardized mortality ratios for total cancers for both periods combined were 138 for men (101 observed deaths) and 148 for women (86 observed deaths). These excesses were statistically significant (p less than 0.05). However, after review of data from the actual death certificates, city maps, and information from city officials, 44 of the 187 total cancer deaths (24%) were found to have had an incorrectly reported or coded residence status. After removal of these cases, the standardized mortality ratio for total cancers for males went from 138 to 107, and for females the standardized mortality ratio went from 148 to 111. No standardized mortality ratios remained statistically significant. These findings may have implications for those who use mortality data for assessing cancer rates in communities in rural areas.

Death Certificates↗
PubMed1990

Appropriate public health responses to clusters: the art of being responsibly responsive.

Between 1981 and 1988, the Minnesota Department of Health actively responded to over 400 reports from persons concerned about disease occurrence in their community, school, or workplace. Almost all of these reports involved perceived excesses of cases of cancer. Although there is little potential for identifying unsuspected public health problems or developing new etiologic insights, the Minnesota Department of Health has found that responding to reported clusters is a legitimate and necessary public health activity. To be responsibly responsive to these concerns, the Department has developed four steps to prioritize investigation of reported disease clusters, as well as six criteria for determination of the feasibility of environmental epidemiologic investigations. Approximately 95% of all concerns have been handled within the first two steps of this approach, generally requiring only education, or sometimes examination of readily-available data. Less than 5% of the concerns have required additional data collection and evaluation, and only about 1% have resulted in full-scale epidemiologic studies. Successful conclusions at all levels of this process require that public health officials develop effective communication, maintain objectivity, and provide leadership for controversial and difficult issues.

Clinical Protocols↗
PubMed1989

Minnesota highway maintenance worker cohort mortality study: methods and noncancer mortality.

In 1984, the Minnesota Department of Health (MDH) began a cohort mortality study of 4,849 workers to follow up concerns with the health and safety of highway maintenance workers (HMWs). A total of 1,530 deaths had occurred, resulting in a standardized mortality ratio (SMR) of 91 (p less than .01) and an all cancer SMR of 84 (p less than .01). There was a significant elevation in the SMR for chronic renal failure among long-term rural workers (SMR = 676, p less than .05). The SMR was also elevated for transportation injuries. The latter SMR was highest among short-term urban workers (SMR = 280, p less than .01). In addition, the SMR for transportation-related injury deaths tended to increase the later the decade of starting work. The SMRs were 137, 259, 502, and 2,145 for urban workers starting work in the decades 1945-1954, 1955-1964, 1965-1974, and 1975-1984, respectively. This study demonstrates the possible adverse health effects of highway maintenance work and the need to comprehensively evaluate injury mortality among selected occupational cohorts.

Accidents, Traffic↗
PubMed1989

Minnesota Highway Maintenance Worker Study: cancer mortality.

Highway maintenance workers (HMWs) have been exposed to a broad range of potentially toxic substances, including diesel fuels and exhaust, asphalts and tars, herbicides, gasoline, polynuclear aromatic hydrocarbons, benzene, and lead. The number of current and former state, county, and municipal HMWs in the United States exceeds 500,000, yet the health risks of this occupation had never been studied. To fill this void and to respond to the public perception that Minnesota HMWs were at high risk of developing leukemia, an occupational cohort mortality study was conducted of Minnesota HMWs employed between 1945 and 1984. Leukemia mortality in HMWs with 30-39 years of work (standardized mortality ratio [SMR] = 425; 95% confidence interval [CI] = 171-876) and urologic cancer mortality in HMWs with 40-49 year latency (SMR = 292; CI = 117-602) were significantly elevated. The extent to which these and other findings were directly related to work exposures is unknown. Further investigations to resolve the significance of the risks associated with the HMW occupation are currently underway.

Cohort Studies↗
PubMed1988

Usefulness of comprehensive feasibility studies in environmental epidemiology investigations: a case study in Minnesota.

Episodes of public water supply contamination with industrial or agricultural chemicals frequently give rise to public concerns about adverse health effects. These concerns may precipitate epidemiologic or clinical investigations requiring large expenditures of state and federal resources regardless of whether such investigations are justified by scientific criteria. An alternative is a comprehensive feasibility study, utilizing all available information to determine whether large-scale studies are warranted or feasible. At a relatively modest cost, a feasibility study allows health officials to identify information needs and deficiencies, outline potential study options and costs, clearly establish the rationale for a proposed study or, conversely, prevent unwarranted expenditures of public resources. Furthermore, a feasibility study may in itself resolve many community and scientific concerns. This article provides a case study of the usefulness of a formal feasibility study in a situation involving an elevated cancer rate and contaminated municipal water supply wells surrounding a federal superfund site.

Costs and Cost Analysis↗
PubMed1985

Lead toxicity.

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Adult↗